Optically functional film

ABSTRACT

Provided is an optically functional film that can contribute to the widening of the color gamut of an image display apparatus, the optically functional film being suppressed in brightness reduction and being excellent in durability. The optically functional film of the present invention includes an optically functional layer having a moisture permeability of 100 g/m2 or less, wherein the optically functional layer has an absorption peak in a wavelength band in a range of from 580 nm to 610 nm, and wherein the optically functional layer contains a compound X represented by the general formula (I) or the general formula (II).

TECHNICAL FIELD

The present invention relates to an optically functional film.

BACKGROUND ART

In recent years, an image display apparatus has been required to achievelightness and vividness (i.e., color gamut widening), and hence anorganic EL display apparatus (OLED) has been attracting attention.However, a liquid crystal display apparatus has also been required toachieve color gamut widening. For example, as a method of widening thecolor gamut of an image display apparatus, such as a liquid crystaldisplay apparatus, a method including arranging a color correctionfilter showing an absorption maximum wavelength in a specific wavelengthrange on the viewer side of the image display apparatus has beenproposed (Patent Literature 1). In the related art method, however, aproblem of a reduction in brightness caused by the absorption of lightby the color correction filter, a problem with durability in which thecolor of the color correction filter containing a coloring matterdeteriorates over time, and the like occur.

CITATION LIST Patent Literature

[PTL 1] JP 2009-251511 A

SUMMARY OF INVENTION Technical Problem

The present invention has been made to solve the conventional problems,and a primary object of the present invention is to provide an opticallyfunctional film that can contribute to the widening of the color gamutof an image display apparatus, the optically functional film beingsuppressed in brightness reduction and being excellent in durability.

Solution to Problem

According to one embodiment of the present invention, there is providedan optically functional film, including an optically functional layerhaving a moisture permeability of 100 g/m² or less, wherein theoptically functional layer has an absorption peak in a wavelength bandin a range of from 580 nm to 610 nm, and wherein the opticallyfunctional layer contains a compound X represented by the followinggeneral formula (I) or general formula (II):

in the formula (I),

R₁, R₂, R₃, R₄, R₅, R₆, R₇, and R₈ each independently represent ahydrogen atom, a halogen atom, a substituted or unsubstituted alkylgroup having 1 or more and 20 or less carbon atoms, a substituentrepresented by the formula (a), or a substituent represented by theformula (b),

R₁ and R₂ form a saturated cyclic skeleton including 5 or 6 carbonatoms, and R₃, R₄, R₅, R₆, R₇, and R₈ each independently represent ahydrogen atom, a halogen atom, which is preferably Cl, a substituted orunsubstituted alkyl group having 1 or more and 20 or less carbon atoms,a substituent represented by the formula (a), or a substituentrepresented by the formula (b),

R₂ and R₃ form a saturated cyclic skeleton including 5 to 7 carbonatoms, and R₁, R₄, R₅, R₆, R₇, and R₈ each independently represent ahydrogen atom, a halogen atom, which is preferably Cl, a substituted orunsubstituted alkyl group having 1 or more and 20 or less carbon atoms,a substituent represented by the formula (a), or a substituentrepresented by the formula (b),

R₅ and R₆ form a saturated cyclic skeleton including 5 or 6 carbonatoms, and R₁, R₂, R₃, R₄, R₇, and R₈ each independently represent ahydrogen atom, a halogen atom, which is preferably Cl, a substituted orunsubstituted alkyl group having 1 or more and 20 or less carbon atoms,a substituent represented by the formula (a), or a substituentrepresented by the formula (b),

R₆ and R₇ form a saturated cyclic skeleton including 5 to 7 carbonatoms, and R₁, R₂, R₃, R₄, R₅, and R₈ each independently represent ahydrogen atom, a halogen atom, which is preferably Cl, a substituted orunsubstituted alkyl group having 1 or more and 20 or less carbon atoms,a substituent represented by the formula (a), or a substituentrepresented by the formula (b),

R₁ and R₂ form a saturated cyclic skeleton including 5 or 6 carbonatoms, R₅ and R₆ form a saturated cyclic skeleton including 5 or 6carbon atoms, and R₃, R₄, R₇, and R₈ each independently represent ahydrogen atom, a halogen atom, which is preferably Cl, a substituted orunsubstituted alkyl group having 1 or more and 20 or less carbon atoms,a substituent represented by the formula (a), or a substituentrepresented by the formula (b), or

R₂ and R₃ form a saturated cyclic skeleton including 5 to 7 carbonatoms, R₆ and R₇ form a saturated cyclic skeleton including 5 to 7carbon atoms, and R₁, R₄, R₅, and R₈ each independently represent ahydrogen atom, a halogen atom, which is preferably Cl, a substituted orunsubstituted alkyl group having 1 or more and 20 or less carbon atoms,a substituent represented by the formula (a), or a substituentrepresented by the formula (b); and

in the formula (II), R₄ and R₈ each independently represent a hydrogenatom, or a substituted or unsubstituted alkyl group having 1 or more and20 or less carbon atoms.

In one embodiment, the optically functional film further includes apressure-sensitive adhesive layer arranged on at least one side of theoptically functional layer.

In one embodiment, the optically functional film further includes asubstrate arranged on at least one side of the optically functionallayer.

According to another embodiment of the present invention, there isprovided an image display apparatus. The image display apparatusincludes the optically functional film.

Advantageous Effects of Invention

According to the present invention, the optically functional film thatcan contribute to the widening of the color gamut of the image displayapparatus, which is suppressed in brightness reduction and is excellentin durability, can be provided.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1(a) to FIG. 1(c) are each a schematic sectional view of anoptically functional film according to one embodiment of the presentinvention.

DESCRIPTION OF EMBODIMENTS

Now, preferred embodiments of the present invention are described.However, the present invention is not limited to these embodiments.

A. Optically Functional Film

FIG. 1(a) is a schematic sectional view of an optically functional filmaccording to one embodiment of the present invention. An opticallyfunctional film 100 of this embodiment includes an optically functionallayer 10. The optically functional layer 10 has a moisture permeabilityof 100 g/m² or less. The optically functional layer 10 has an absorptionpeak in a wavelength band in the range of from 580 nm to 610 nm. Suchoptically functional layer may be obtained by incorporating apredetermined coloring matter into the optically functional layer. Theoptically functional film may include any appropriate member in additionto the optically functional layer. For example, the optically functionalfilm may include a pressure-sensitive adhesive layer or a substrate asdescribed later.

FIG. 1(b) is a schematic sectional view of an optically functional filmaccording to another embodiment of the present invention. An opticallyfunctional film 100′ of this embodiment further includes apressure-sensitive adhesive layer 20 on at least one side of theoptically functional layer 10. FIG. 1(c) is a schematic sectional viewof an optically functional film according to still another embodiment ofthe present invention. An optically functional film 100″ of thisembodiment further includes a substrate 30 on at least one side of theoptically functional layer 10. The optically functional layer 10 and thesubstrate 30 are typically laminated via the pressure-sensitive adhesivelayer 20.

In the present invention, when the optically functional layerselectively absorbs light in a specific wavelength range (from 580 nm to610 nm) and is suppressed in unneeded absorption in a wavelength rangeexcept the specific wavelength range through the use of a specificcoloring matter to be described later (coloring matter represented bythe general formula (I) or (II)), an optically functional film that cancontribute to the widening of the color gamut of an image displayapparatus and to an improvement in brightness thereof can be obtained.When the optically functional film of the present invention is used, thecolor gamut of the image display apparatus can be significantly widenedwithout use of a high-cost technology (an organic EL technology or aquantum dot technology). In addition, when the moisture permeability ofthe optically functional layer is set to 100 g/m² or less, the opticallyfunctional layer is excellent in durability. Further, even when acoloring matter is used with a view to forming an optically functionallayer having a light absorption characteristic as described above, thecolor deterioration (decomposition) of the coloring matter can besuppressed, and hence the color gamut widening can be stably maintainedover time. The fact that the coloring matter having low durability ismade usable in the optically functional film is one achievement of thepresent invention. When the optically functional film includes any otherlayer, such as a pressure-sensitive adhesive layer, the effect of thepresent invention can be obtained by incorporating the coloring matternot into the other layer but into the optically functional layer havinga low moisture permeability.

A-1. Optically Functional Layer

As described above, the optically functional layer has an absorptionpeak in the wavelength band in the range of from 580 nm to 610 nm. Theformation of such optically functional layer can provide an opticallyfunctional film that can contribute to the widening of the color gamutof an image display apparatus and to an improvement in brightnessthereof. The absorption spectrum of the film may be measured with aspectrophotometer (manufactured by Hitachi High-TechnologiesCorporation, product name: “U-4100”).

The ratio (A₅₄₅/A_(max)) of the absorbance A₅₄₅ of the peak of theoptically functional layer at a wavelength of 545 nm to the absorbanceA_(max) of the highest absorption peak of the optically functional layerat a wavelength of from 580 nm to 610 nm is preferably 0.13 or less,more preferably 0.12 or less, still more preferably 0.11 or less,particularly preferably 0.1 or less. When an optically functional layerhaving a small absorbance at a wavelength of 545 nm as described aboveis formed, an optically functional film that can contribute to thewidening of the color gamut of an image display apparatus by absorbinglight that is not needed for color representation can be obtained. Inaddition, the film hardly absorbs light emitted from a light sourcewhose wavelength is around 545 nm at which a visibility is high, andhence can be suppressed in brightness reduction.

In the optically functional layer, the half width of the absorption peakin the wavelength range of from 580 nm to 610 nm is preferably 35 nm orless, more preferably 30 nm or less, still more preferably 25 nm orless, particularly preferably 20 nm or less. When the half width fallswithin such ranges, an optically functional film that can contribute tothe widening of the color gamut of an image display apparatus can beobtained.

In one embodiment, the optically functional layer is free of anabsorption peak in the range of from 530 nm to 570 nm. Morespecifically, the optically functional layer is free of an absorptionpeak having an absorbance of 0.1 or more in the range of from 530 nm to570 nm. The formation of such optically functional layer can provide anoptically functional film that can contribute to the widening of thecolor gamut of an image display apparatus.

In one embodiment, the optically functional layer further has anabsorption peak in a wavelength band in the range of from 440 nm to 510nm. That is, in this embodiment, the optically functional layer hasabsorption peaks in the wavelength bands in the ranges of from 440 nm to510 nm and from 580 nm to 610 nm. With such configuration, the colormixing of red light and green light, and that of green light and bluelight can be satisfactorily prevented. When the optically functionalfilm configured as described above is applied to an image displayapparatus, the color gamut of the image display apparatus can bewidened, and hence bright and vivid image quality can be obtained. Anoptically functional layer having two or more absorption peaks asdescribed above may be obtained by using a plurality of kinds ofcoloring matters.

The transmittance of the optically functional layer at an absorptionpeak is preferably from 0% to 80%, more preferably from 0% to 70%. Whenthe transmittance falls within such ranges, the above-mentioned effectof the present invention becomes more significant.

The visible light transmittance of the optically functional layer ispreferably from 30% to 90%, more preferably from 30% to 80%. When thevisible light transmittance falls within such ranges, an opticallyfunctional film that can widen the color gamut of an image displayapparatus while being suppressed in brightness reduction can beobtained.

As described above, the moisture permeability of the opticallyfunctional layer is 100 g/m² or less. The moisture permeability of theoptically functional layer is preferably 90 g/m² or less, morepreferably 80 g/m² or less, still more preferably 70 g/m² or less.Although the moisture permeability of the optically functional layer ispreferably as low as possible, its lower limit is, for example, 0.5g/m². The term “moisture permeability” as used herein refers to a valueobtained by measuring the amount (g) of water vapor, which passes asample having an area of 1 m² in 24 hours in an atmosphere having atemperature of 40° C. and a humidity of 92% RH, in conformity with themoisture permeability test (cup method) of JIS Z 0208.

The thickness of the optically functional layer is typically from 0.1 μmto 100 μm, preferably from 1 μm to 100 μm, more preferably from 2 μm to50 μm, still more preferably from 5 μm to 35 μm.

The optically functional layer may be formed from a resin compositioncontaining a resin and a coloring matter.

Resin

Any appropriate resin is used as the resin for forming the opticallyfunctional layer as long as an optically functional layer having amoisture permeability of 100 g/m² or less can be formed. As the resinfor forming the optically functional layer, there may be used, forexample: a (meth)acrylic resin; a cycloolefin-based resin, such as anorbornene-based resin; an olefin-based resin, such as polyethylene orpolypropylene; or a polyester-based resin, such as polyethyleneterephthalate (PET) because any such resin can satisfy theabove-mentioned moisture permeability. Of those, a (meth)acrylic resinor a cycloolefin-based resin is preferably used. The “(meth)acrylicresin” refers to an acrylic resin and/or a methacrylic resin.

Any appropriate (meth)acrylic resin is used as the (meth)acrylic resin.Examples thereof include a poly(meth)acrylic acid ester, such aspolymethyl methacrylate, a methyl methacrylate-(meth)acrylic acidcopolymer, a methyl methacrylate-(meth)acrylic acid ester copolymer, amethyl methacrylate-acrylic acid ester-(meth)acrylic acid copolymer, amethyl (meth)acrylate-styrene copolymer (e.g., an MS resin), and apolymer having an alicyclic hydrocarbon group (e.g., a methylmethacrylate-cyclohexyl methacrylate copolymer or a methylmethacrylate-norbornyl (meth)acrylate copolymer). A preferred examplethereof is a poly(C1-C6)alkyl (meth)acrylate, such as polymethyl(meth)acrylate. Amore preferred example thereof is a methylmethacrylate-based resin including methyl methacrylate as a maincomponent (at from 50 wt % to 100 wt %, preferably from 70 wt % to 100wt %).

Specific examples of the (meth)acrylic resin include: ACRYPET VH andACRYPET VRL20A manufactured by Mitsubishi Rayon Co., Ltd.; and a high-Tg(meth)acrylic resin obtained through intramolecular cross-linking or anintramolecular cyclization reaction.

In one embodiment, a (meth)acrylic resin having a glutaric anhydridestructure, a (meth)acrylic resin having a lactone ring structure, or a(meth)acrylic resin having a glutarimide structure is preferred as the(meth)acrylic resin because any such resin has high heat resistance,high transparency, and high mechanical strength.

Examples of the (meth)acrylic resin having a glutaric anhydridestructure include (meth)acrylic resins each having a glutaric anhydridestructure described in, for example, JP 2006-283013 A, JP 2006-335902 A,and JP 2006-274118 A.

Examples of the (meth)acrylic resin having a lactone ring structureinclude (meth)acrylic resins each having a lactone ring structuredescribed in, for example, JP 2000-230016 A, JP 2001-151814 A, JP2002-120326 A, JP 2002-254544 A, and JP 2005-146084 A.

Examples of the (meth)acrylic resin having a glutarimide structureinclude (meth)acrylic resins each having a glutarimide structuredescribed in, for example, JP 2006-309033A, JP 2006-317560 A, JP2006-328329 A, JP 2006-328334 A, JP 2006-337491 A, JP 2006-337492A, JP2006-337493 A, JP 2006-337569A, and JP 2007-009182 A.

The cycloolefin-based resin is, for example, a norbornene-based resin.The norbornene-based resin refers to a (co)polymer obtained by using anorbornene-based monomer having a norbornene ring as part or theentirety of starting materials (monomers). Examples of thenorbornene-based monomer include: norbornene, alkyl and/or alkylidenesubstituted products thereof, such as 5-methyl-2-norbornene,5-dimethyl-2-norbornene, 5-ethyl-2-norbornene, 5-butyl-2-norbornene, and5-ethylidene-2-norbornene, and polar group (e.g., halogen) substitutedproducts thereof; dicyclopentadiene and 2,3-dihydrodicyclopentadiene;dimethanooctahydronaphthalene, alkyl and/or alkylidene substitutedproducts thereof, and polar group (e.g., halogen) substituted productsthereof, such as

-   6-methyl-1,4:5,8-dimethano-1,4,4a,5,6,7,8,8a-octahydronaphthalene,-   6-ethyl-1,4:5,8-dimethano-1,4,4a,5,6,7,8,8a-octahydronaphthalene,-   6-ethylidene-1,4:5,8-dimethano-1,4,4a,5,6,7,8,8a-octahydronaphthalene,-   6-chloro-1,4:5,8-dimethano-1,4,4a,5,6,7,8,8a-octahydronaphthalene,-   6-cyano-1,4:5,8-dimethano-1,4,4a,5,6,7,8,8a-octahydronaphthalene,-   6-pyridyl-1,4:5,8-dimethano-1,4,4a,5,6,7,8,8a-octahydronaphthalene,    and-   6-methoxycarbonyl-1,4:5,8-dimethano-1,4,4a,5,6,7,8,8a-octahydronaphthalene;    and trimers or tetramers of cyclopentadiene, such as-   4,9:5,8-dimethano-3a,4,4a,5,8,8a,9,9a-octahydro-1H-benzoindene and-   4,11:5,10:6,9-trimethano-3a,4,4a,5,5a,6,9,9a,10,10a,11,11a-dodecahydro-1H-cyclopentaanthracene.

Various products are commercially available as the norbornene-basedresin. Specific examples thereof include: products available under theproduct names “ZEONEX” and “ZEONOR” from Zeon Corporation; a productavailable under the product name “Arton” from JSR Corporation; a productavailable under the product name “TOPAS” from TICONA; and a productavailable under the product name “APEL” from Mitsui Chemicals, Inc.

The optically functional layer may contain an additive. Examples of theadditive include: antioxidants, such as hindered phenol-based,phosphorus-based, and sulfur-based antioxidants; stabilizers, such as alight stabilizer, a weathering stabilizer, and a heat stabilizer;reinforcing materials, such as glass fibers and carbon fibers; anear-infrared ray absorber; flame retardants, such astris(dibromopropyl) phosphate, triallyl phosphate, and antimony oxide;antistatic agents, such as anionic, cationic, and nonionic surfactants;colorants, such as an inorganic pigment, an organic pigment, and a dye;an organic filler and an inorganic filler; a resin modifier; an organicfiller and an inorganic filler; a plasticizer; a lubricant; anantistatic agent; a flame retardant; and a retardation-reducing agent.

Although a method of producing the optically functional layer is notparticularly limited, for example, the following may be adopted: theresin and any other polymer, additive, or the like are sufficientlymixed with each other by any appropriate mixing method to provide athermoplastic resin composition in advance, and then the composition isformed into a film. Alternatively, the following maybe adopted: theresin and the other polymer, additive, or the like are turned intosolutions separate from each other, and then the solutions are mixed toprovide a uniform mixed liquid, followed by the forming of the mixedliquid into a film.

To produce the thermoplastic resin composition, for example, theabove-mentioned film raw materials are pre-blended with any appropriatemixer, such as an omni mixer, and then the resultant mixture is extrudedand kneaded. In this case, a mixer to be used in the extrusion and thekneading is not particularly limited, and any appropriate mixersincluding an extruder, such as a uniaxial extruder or a biaxialextruder, and a pressure kneader may each be used.

As a method for the film forming, there is given, for example, anyappropriate film forming method, such as a solution casting method, amelt extrusion method, a calender method, or a compression moldingmethod. Of those film forming methods, a solution casting method and amelt extrusion method are preferred.

As a solvent to be used in the solution casting method, there are given,for example: aromatic hydrocarbons, such as benzene, toluene, andxylene; aliphatic hydrocarbons, such as cyclohexane and decalin; esters,such as ethyl acetate and butyl acetate; ketones, such as acetone,methyl ethyl ketone, and methyl isobutyl ketone; alcohols, such asmethanol, ethanol, isopropanol, butanol, isobutanol, methyl cellosolve,ethyl cellosolve, and butyl cellosolve; ethers, such as tetrahydrofuranand dioxane; halogenated hydrocarbons, such as dichloromethane,chloroform, and carbon tetrachloride; dimethylformamide; anddimethylsulfoxide. Those solvents may be used alone or in combinationthereof.

As an apparatus for performing the solution casting method, there aregiven, for example, a drum-type casting machine, a band-type castingmachine, and a spin coater.

Examples of the melt extrusion method include a T-die method and aninflation method. A forming temperature is preferably from 150° C. to350° C., more preferably from 200° C. to 300° C.

When the film forming is performed by the T-die method, a roll-shapedfilm may be obtained by: attaching a T-die to the tip portion of a knownuniaxial extruder or biaxial extruder; and winding a film extruded intoa film shape. At this time, uniaxial stretching may be performed byappropriately adjusting the temperature of a winding roll and stretchingthe film in its extrusion direction. In addition, simultaneous biaxialstretching, sequential biaxial stretching, or the like may be performedby stretching the film in a direction perpendicular to the extrusiondirection.

Coloring Matter

The optically functional layer contains one or more kinds of coloringmatters.

The optically functional layer contains, as a coloring matter, acompound X represented by the following general formula (I) or generalformula (II). The compound X is a compound having an absorption peak inthe wavelength band in the range of from 580 nm to 610 nm.

in the formula (I),

R₁, R₂, R₃, R₄, R₅, R₆, R₇, and R₈ each independently represent ahydrogen atom, a halogen atom, a substituted or unsubstituted alkylgroup having 1 or more and 20 or less carbon atoms, a substituentrepresented by the formula (a), or a substituent represented by theformula (b),

R₁ and R₂ form a saturated cyclic skeleton including 5 or 6 carbonatoms, and R₃, R₄, R₅, R₆, R₇, and R₈ each independently represent ahydrogen atom, a halogen atom, which is preferably Cl, a substituted orunsubstituted alkyl group having 1 or more and 20 or less carbon atoms,a substituent represented by the formula (a), or a substituentrepresented by the formula (b),

R₂ and R₃ form a saturated cyclic skeleton including 5 to 7 carbonatoms, and R₁, R₄, R₅, R₆, R₇, and R₈ each independently represent ahydrogen atom, a halogen atom, which is preferably Cl, a substituted orunsubstituted alkyl group having 1 or more and 20 or less carbon atoms,a substituent represented by the formula (a), or a substituentrepresented by the formula (b),

R₅ and R₆ form a saturated cyclic skeleton including 5 or 6 carbonatoms, and R₁, R₂, R₃, R₄, R₇, and R₈ each independently represent ahydrogen atom, a halogen atom, which is preferably Cl, a substituted orunsubstituted alkyl group having 1 or more and 20 or less carbon atoms,a substituent represented by the formula (a), or a substituentrepresented by the formula (b),

R₆ and R₇ form a saturated cyclic skeleton including 5 to 7 carbonatoms, and R₁, R₂, R₃, R₄, R₅, and R₈ each independently represent ahydrogen atom, a halogen atom, which is preferably Cl, a substituted orunsubstituted alkyl group having 1 or more and 20 or less carbon atoms,a substituent represented by the formula (a), or a substituentrepresented by the formula (b),

R₁ and R₂ form a saturated cyclic skeleton including 5 or 6 carbonatoms, R₅ and R₆ form a saturated cyclic skeleton including 5 or 6carbon atoms, and R₃, R₄, R₇, and R₈ each independently represent ahydrogen atom, a halogen atom, which is preferably Cl, a substituted orunsubstituted alkyl group having 1 or more and 20 or less carbon atoms,a substituent represented by the formula (a), or a substituentrepresented by the formula (b), or

R₂ and R₃ form a saturated cyclic skeleton including 5 to 7 carbonatoms, R₆ and R₇ form a saturated cyclic skeleton including 5 to 7carbon atoms, and R₁, R₄, R₅, and R₈ each independently represent ahydrogen atom, a halogen atom, which is preferably Cl, a substituted orunsubstituted alkyl group having 1 or more and 20 or less carbon atoms,a substituent represented by the formula (a), or a substituentrepresented by the formula (b); and

in the formula (II), R₄ and R₈ each independently represent a hydrogenatom, or a substituted or unsubstituted alkyl group having 1 or more and20 or less carbon atoms.

The saturated cyclic skeleton (number of carbon atoms: 5 or 6) formed soas to include R₁ and R₂, and the saturated cyclic skeleton (number ofcarbon atoms: 5 or 6) formed so as to include R₅ and R₆ may each have asubstituent. The substituent is, for example, an alkyl group having 1 to4 carbon atoms. In addition, the saturated cyclic skeleton (number ofcarbon atoms: 5 to 7) formed so as to include R₂ and R₃, and thesaturated cyclic skeleton (number of carbon atoms: 5 to 7) formed so asto include R₆ and R₇ may each have a substituent. The substituent is,for example, an alkyl group having 1 to 4 carbon atoms.

In one embodiment, R₄ and/or R₈ has a benzene ring or a naphthalene ringas a substituent.

Specific examples of the compound X represented by the formula (I) or(II) include compounds represented by the following general formulae(I-1) to (I-27) and (II-1). The absorption peak of the compound X isshown in each of the following tables. With regard to each of theformulae (I-1) to (I-23), an absorption peak obtained by measuring theabsorbance of a film formed of a resin composition prepared by mixingaliphatic polycarbonate with the compound X is shown, and with regard toeach of the formulae (I-24) to (I-27) and (II-1), an absorption peakobtained by measuring the absorbance of a film formed of a resincomposition prepared by mixing a polymethyl methacrylate resin with thecompound X is shown.

Absorption peak NO. Compound X (nm) I-1

596 nm (APC) I-2

595 nm (APC) I-3

582 nm (APC) I-4

585 nm (APC) I-5

585 nm (APC) I-6

575 nm (APC) I-7

585 nm (APC) I-8

587 nm (APC) I-9

587 nm (APC) I-10

588 nm (APC) I-11

588 nm (APC) I-12

589 nm (APC) I-13

592 nm (APC) I-14

591 nm (APC) I-15

595 nm (APC) I-16

595 nm (APC) I-17

596 nm (APC) I-18

614 nm (APC) I-19

581 nm (APC) I-20

591 nm (APC) I-21

593 nm (APC) I-22

594 nm (APC) I-23

594 nm (APC) I-24

592 nm I-25

593 nm I-26

594 nm I-27

594 nm II-1

597 nm

The content of the compound X is preferably from 0.01 part by weight to50 parts by weight, more preferably from 0.05 part by weight to 10 partsby weight, still more preferably from 0.1 part by weight to 5 parts byweight, particularly preferably from 0.1 part by weight to 1 part byweight with respect to 100 parts by weight of the resin.

The compound X is a compound that is typically difficult to use as anadditive for an optical member because the compound has the followingfeature: the compound is liable to alter (its color is liable todeteriorate) under the influence of moisture, oxygen, or the like.According to the present invention, however, even when an opticallyfunctional layer containing the compound X is formed, the deteriorationof the optically functional layer over time can be prevented.

The optically functional layer may further contain a compound having anabsorption peak in the wavelength band in the range of from 440 nm to510 nm. For example, an anthraquinone-based, oxime-based,naphthoquinone-based, quinizarin-based, oxonol-based, azo-based,xanthene-based, or phthalocyanine-based compound (dye) is used as suchcompound.

The content of the compound having an absorption peak in the wavelengthband in the range of from 440 nm to 510 nm is preferably from 0.01 partby weight to 50 parts by weight, more preferably from 0.01 part byweight to 25 parts by weight with respect to 100 parts by weight of theresin.

A-2. Pressure-sensitive Adhesive Layer

The pressure-sensitive adhesive layer includes any appropriatepressure-sensitive adhesive. The pressure-sensitive adhesive preferablyhas transparency and optical isotropy. Specific examples of thepressure-sensitive adhesive include a rubber-based pressure-sensitiveadhesive, an acrylic pressure-sensitive adhesive, a silicone-basedpressure-sensitive adhesive, an epoxy-based pressure-sensitive adhesive,and a cellulose-based pressure-sensitive adhesive. Of those, arubber-based pressure-sensitive adhesive or an acrylicpressure-sensitive adhesive is preferred.

A rubber-based polymer serving as the rubber-based pressure-sensitiveadhesive is a polymer showing rubber elasticity in a temperature regionaround room temperature. Preferred examples of the rubber-based polymer(A) include a styrene-based thermoplastic elastomer (A1), anisobutylene-based polymer (A2), and a combination thereof.

Examples of the styrene-based thermoplastic elastomer (A1) may includestyrene-based block copolymers, such as astyrene-ethylene-butylene-styrene block copolymer (SEBS), astyrene-isoprene-styrene block copolymer (SIS), astyrene-butadiene-styrene block copolymer (SBS), astyrene-ethylene-propylene-styrene block copolymer (SEPS, a hydrogenatedproduct of SIS), a styrene-ethylene-propylene block copolymer (SEP, ahydrogenated product of a styrene-isoprene block copolymer), astyrene-isobutylene-styrene block copolymer (SIBS), and astyrene-butadiene rubber (SBR). Of those, astyrene-ethylene-propylene-styrene block copolymer (SEPS, a hydrogenatedproduct of SIS), a styrene-ethylene-butylene-styrene block copolymer(SEBS), and a styrene-isobutylene-styrene block copolymer (SIBS) arepreferred because the copolymers each have polystyrene blocks at bothends of a molecule thereof and have a high cohesive force as a polymer.A commercial product maybe used as the styrene-based thermoplasticelastomer (A1). Specific examples of the commercial product includeSEPTON and HYBRAR manufactured by Kuraray Co., Ltd., Tuftec manufacturedby Asahi Kasei Chemicals Corporation, and SIBSTAR manufactured by KanekaCorporation.

The weight-average molecular weight of the styrene-based thermoplasticelastomer (A1) is preferably from about 50,000 to about 500,000, morepreferably from about 50,000 to about 300,000, still more preferablyfrom about 50,000 to about 250,000. The weight-average molecular weightof the styrene-based thermoplastic elastomer (A1) preferably fallswithin such ranges because both of the cohesive force andviscoelasticity of the polymer can be achieved.

A styrene content in the styrene-based thermoplastic elastomer (A1) ispreferably from about 5 wt % to about 70 wt %, more preferably fromabout 5 wt % to about 40 wt %, still more preferably from about 10 wt %to about 20 wt %. The styrene content in the styrene-based thermoplasticelastomer (A1) preferably falls within such ranges becauseviscoelasticity based on a soft segment can be secured while a cohesiveforce based on a styrene moiety is maintained.

Examples of the isobutylene-based polymer (A2) may include polymers eachincluding isobutylene as a constituent monomer and having aweight-average molecular weight (Mw) of preferably 500,000 or more. Theisobutylene-based polymer (A2) may be a homopolymer of isobutylene(polyisobutylene, PIB) or may be a copolymer including isobutylene as amain monomer (i.e., a copolymer obtained by copolymerizing isobutyleneat a ratio of more than 50 mol %). Examples of such copolymer mayinclude a copolymer of isobutylene and normal butylene, a copolymer ofisobutylene and isoprene (e.g., a butyl rubber, such as a regular butylrubber, a chlorinated butyl rubber, a brominated butyl rubber, or apartially cross-linked butyl rubber), and vulcanized products andmodified products thereof (e.g., a product modified with a functionalgroup, such as a hydroxyl group, a carboxyl group, an amino group, or anepoxy group). Of those, polyisobutylene (PIB) is preferred because thepolyisobutylene is free of a double bond in its main chain, and isexcellent in weatherability. A commercial product may be used as theisobutylene-based polymer (A2). The commercial product is specifically,for example, OPPANOL manufactured by BASF.

The weight-average molecular weight (Mw) of the isobutylene-basedpolymer (A2) is preferably 500,000 or more, more preferably 600,000 ormore, still more preferably 700,000 or more. In addition, the upperlimit of the weight-average molecular weight (Mw) is preferably5,000,000 or less, more preferably 3,000,000 or less, still morepreferably 2,000,000 or less. When the weight-average molecular weightof the isobutylene-based polymer (A2) is set to 500,000 or more, apressure-sensitive adhesive that is more excellent in durability at thetime of its high-temperature storage can be obtained.

The content of the rubber-based polymer (A) in the pressure-sensitiveadhesive is preferably 30 wt % or more, more preferably 40 wt % or more,still more preferably 50 wt % or more, particularly preferably 60 wt %or more in the total solid content of the pressure-sensitive adhesive.The upper limit of the content of the rubber-based polymer is preferably95 wt % or less, more preferably 90 wt % or less.

In the rubber-based pressure-sensitive adhesive, the rubber-basedpolymer (A) and any other rubber-based polymer may be used incombination. Specific examples of the other rubber-based polymerinclude: a butyl rubber (IIR), a butadiene rubber (BR), anacrylonitrile-butadiene rubber (NBR), EPR (binary ethylene-propylenerubber), EPT (ternary ethylene-propylene rubber), an acrylic rubber, aurethane rubber, and a polyurethane-based thermoplastic elastomer; apolyester-based thermoplastic elastomer; and a blend-based thermoplasticelastomer, such as a polymer blend of polypropylene and EPT (ternaryethylene-propylene rubber). The compounding amount of the otherrubber-based polymer is preferably about 10 parts by weight or less withrespect to 100 parts by weight of the rubber-based polymer (A).

The acrylic polymer of the acrylic pressure-sensitive adhesive typicallycontains an alkyl (meth)acrylate as a main component, and may contain anaromatic ring-containing (meth)acrylate, an amide group-containingmonomer, a carboxyl group-containing monomer, and/or a hydroxylgroup-containing monomer as a copolymerization component in accordancewith a purpose. The term “(meth)acrylate” as used herein means anacrylate and/or a methacrylate. The alkyl (meth)acrylate may be, forexample, an alkyl (meth)acrylate having a linear or branched alkyl grouphaving 1 to 18 carbon atoms. The aromatic ring-containing (meth)acrylateis a compound containing an aromatic ring structure in its structure andcontaining a (meth)acryloyl group. The aromatic ring is, for example, abenzene ring, a naphthalene ring, or a biphenyl ring. The aromaticring-containing (meth)acrylate satisfies durability and can alleviatedisplay unevenness due to a white void of the peripheral portion of animage display apparatus. The amide group-containing monomer is acompound containing an amide group in its structure and containing apolymerizable unsaturated double bond, such as a (meth)acryloyl group ora vinyl group. The carboxyl group-containing monomer is a compoundcontaining a carboxyl group in its structure and containing apolymerizable unsaturated double bond, such as a (meth)acryloyl group ora vinyl group. The hydroxyl group-containing monomer is a compoundcontaining a hydroxyl group in its structure and containing apolymerizable unsaturated double bond, such as a (meth)acryloyl group ora vinyl group. Details about the acrylic pressure-sensitive adhesive aredescribed in, for example, JP 2015-199942 A, the description of which isincorporated herein by reference.

A-3. Substrate

Examples of the substrate include: a separator to be arranged forprotecting the pressure-sensitive adhesive layer until the opticallyfunctional film is used; a glass film; and an optical film, such as aretardation film or a polarizing plate.

In one embodiment, a glass film is used as the substrate.

Any appropriate glass film may be adopted as the glass film. Accordingto classification based on composition, examples of the glass filminclude soda-lime glass, borate glass, aluminosilicate glass and quartzglass films. In addition, according to classification based on an alkalicomponent, examples of the glass film include alkali-free glass andlow-alkali glass films. The content of an alkali metal component (e.g.,Na₂O, K₂O, Li₂O) in the glass is preferably 15 wt % or less, morepreferably 10 wt % or less.

The glass film has a thickness of 100 μm or less, preferably 80 μm orless, more preferably 50 μm or less, still more preferably 40 μm orless, particularly preferably 35 μm or less. The lower limit of thethickness of the glass film is preferably 5 μm or more.

The glass film preferably has a light transmittance at a wavelength of550 nm of 85% or more. The glass film preferably has a refractive indexat a wavelength of 550 nm of from 1.4 to 1.65.

The glass film has a density of preferably from 2.3 g/cm³ to 3.0 g/cm³,more preferably from 2.3 g/cm³ to 2.7 g/cm³. When the glass film has adensity falling within the range, an optically functional film can beobtained.

Any appropriate method may be adopted as a forming method for the glassfilm. The glass film is typically produced by melting a mixturecontaining a main raw material, such as silica or alumina, a finingagent, such as salt cake or antimony oxide, and a reducing agent, suchas carbon, at a temperature of from 1,400° C. to 1,600° C., and formingthe molten mixture into a thin sheet shape, followed by cooling.Examples of the forming method for the glass film include a slotdown-draw method, a fusion method, and a float method. The glass filmformed in a sheet shape by any one of those methods may be chemicallypolished with a solvent, such as hydrofluoric acid, as required, inorder to reduce its thickness or enhance its smoothness.

A commercial glass film may be used as it is as the glass film, or thecommercial glass film may be polished into a desired thickness beforeuse. Examples of the commercial glass film include: “7059”, “1737”, or“EAGLE 2000” manufactured by Corning; “AN100” manufactured by AsahiGlass Co., Ltd.; “NA-35” manufactured by NH Techno Glass; “OA-10”manufactured by Nippon Electric Glass Co., Ltd.; and “D263” or “AF45”manufactured by Schott AG.

The oxygen permeability of the substrate is preferably 1 [cm³/(m²·24h·atm)] or less, more preferably 0.8 [cm³/(m²·24 h·atm)] or less, stillmore preferably 0.6 [cm³/(m²·24 h·atm)] or less, particularly preferably0.5 [cm³/(m²·24 h·atm)] or less. When the oxygen permeability fallswithin such ranges, an optically functional film whose opticallyfunctional layer is excellent in durability can be obtained. The oxygenpermeability maybe adjusted by, for example, a material forming thesubstrate or the thickness of the substrate. The oxygen permeability maybe measured under the conditions of 23° C. and 0% RH in conformity withJIS K 7126-2.

G. Image Display Apparatus

An image display apparatus of the present invention includes an imagedisplay panel and the optically functional film. Examples of the imagedisplay panel include a liquid crystal display panel and an organic ELpanel. The optically functional film may be arranged on the viewer sideof the image display panel.

EXAMPLES

Now, the present invention is specifically described byway of Examples.However, the present invention is by no means limited by these Examples.Methods of measuring the respective characteristics are as describedbelow.

(1) Moisture Permeability

The moisture permeability of a layer containing a coloring matter wasmeasured in conformity with JIS Z 0208 (cup method).

(2) Transmittance and Transmittance Change

The transmittance of an optically functional film was measured with ahaze meter (manufactured by Murakami Color Research Laboratory Co.,Ltd., product name: “HM-150”) by a method defined in JIS 7136.

A heating treatment in which the optically functional film was left tostand under an environment at 80° C. for 144 hours was performed, and atransmittance change was determined from the transmittance of theoptically functional film after the heating treatment and the initialtransmittance of the optically functional film immediately after itsproduction by using the expression “{(transmittance after heatingtreatment-initial transmittance)/initial transmittance}×100”.

Example 1

A product available under the product name “DELPET” from Asahi KaseiChemicals Corporation was dissolved in methylene chloride to produce anacrylic resin solution having a solid content concentration of 25%. 100Parts by weight of the acrylic resin was mixed with a resin compositioncontaining 0.1 part by weight of the squaraine compound represented bythe general formula (I-20) to prepare a liquid. The liquid was appliedto a triacetylcellulose substrate having a thickness of 80 μm to providean optically functional layer having a thickness of 7 μm (absorptionmaximum wavelength: 588 nm).

Next, a monomer mixture containing 100 parts by weight of butylacrylate, 0.01 part by weight of 2-hydroxyethyl acrylate, and 5 parts byweight of acrylic acid was loaded into a reaction vessel including acondenser, a nitrogen-introducing tube, a temperature gauge, and astirring apparatus. Further, 0.1 part by weight of2,2′-azobisisobutyronitrile serving as a polymerization initiator wasloaded into 100 parts by weight of the monomer mixture together with 100parts by weight of ethyl acetate. While the mixture was gently stirred,a nitrogen gas was introduced into the vessel to purge air in the vesselwith nitrogen. After that, the temperature of the liquid in the reactionvessel was kept at around 55° C., and a polymerization reaction wasperformed for 8 hours to prepare a solution (solid contentconcentration: 30 wt %) of an acrylic polymer having a weight-averagemolecular weight (Mw) of 1,800,000 and an Mw/Mn of 4.1.

A pressure-sensitive adhesive composition containing 0.23 part by weightof a radical generator (benzoyl peroxide, available under the productname “NYPER BMT” from Nippon Oil & Fats Co., Ltd.) and 1 part by weightof an isocyanate-based cross-linking agent (available under the productname “CORONATE L” from Tosoh Corporation) with respect to 100 parts byweight of the solid content of the acrylic polymer solution produced inthe foregoing was prepared. The pressure-sensitive adhesive compositionwas applied to a separator to form a pressure-sensitive adhesive layerhaving a thickness of 20 μm, and the layer was bonded to the opticalfunctional layer. Finally, the triacetylcellulose substrate was peeled.Thus, an optically functional film was obtained.

The squaraine compound represented by the general formula (I-20) wassynthesized by the following method.

Synthesis of Squaraine Compound

1-Phenyl-1,4,5,6-tetrahydrocyclopenta[b]pyrrole was synthesized by amethod described in “M. Beller et. al., J. Am. Chem. Soc., 2013,135(30), 11384-11388”.

300 Milligrams of 1-phenyl-1,4,5,6-tetrahydrocyclopenta[b]pyrrole and 80mg of squaric acid were mixed in 5 mL of ethanol, and the mixture wasstirred at 80° C. for 2 hours. After that, the mixture was cooled toroom temperature, and the product was filtered out. The product that hadbeen filtered out was washed with ethanol, and was dried under reducedpressure at 70° C. to provide 197 mg of a squaraine compound. Further,the compound was purified by silica gel chromatography to provide 120 mgof a squaraine compound.

The optically functional film (optically functionallayer/pressure-sensitive adhesive layer) obtained as described above wassubjected to the above-mentioned evaluation. The result is shown inTable 1.

Example 2

A cycloolefin-based resin (manufactured by JSR Corporation, productname: “ARTON F4520”) was dissolved in toluene to provide a solutionhaving a solid content of 25%. A resin composition containing 0.2 partby weight of the squaraine compound represented by the general formula(I-20) with respect to 100 parts by weight of the resin solid content ofthe solution was prepared. A film was produced in the same manner as inExample 1 except that its optically functional layer was formed by usingthe resin composition.

The optically functional film (optically functionallayer/pressure-sensitive adhesive layer) obtained as described above wassubjected to the above-mentioned evaluation. The result is shown inTable 1.

Comparative Example 1

A product available under the product name “DELPET” from Asahi KaseiChemicals Corporation was loaded into a uniaxial extruder. The productwas melted and kneaded, and was passed through a T-die to be formed intoa film. The resultant extruded film was subjected to simultaneousbiaxial stretching at a stretching temperature of 240° C. in itslengthwise direction and widthwise direction twice each (area stretchratio: 4.0) to provide an acrylic resin film having a thickness of 40μm.

Next, a monomer mixture containing 100 parts by weight of butylacrylate, 0.01 part by weight of 2-hydroxyethyl acrylate, and 5 parts byweight of acrylic acid was loaded into a reaction vessel including acondenser, a nitrogen-introducing tube, a temperature gauge, and astirring apparatus. Further, 0.1 part by weight of2,2′-azobisisobutyronitrile serving as a polymerization initiator wasloaded into 100 parts by weight of the monomer mixture together with 100parts by weight of ethyl acetate. While the mixture was gently stirred,a nitrogen gas was introduced into the vessel to purge air in the vesselwith nitrogen. After that, the temperature of the liquid in the reactionvessel was kept at around 55° C., and a polymerization reaction wasperformed for 8 hours to prepare a solution (solid contentconcentration: 30 wt %) of an acrylic polymer having a weight-averagemolecular weight (Mw) of 1,800,000 and an Mw/Mn of 4.1.

A pressure-sensitive adhesive composition containing 0.1 part by weightof a squaraine compound represented by the general formula (I-20), 0.23part by weight of a radical generator (benzoyl peroxide, available underthe product name “NYPER BMT” from Nippon Oil & Fats Co., Ltd.), and 1part by weight of an isocyanate-based cross-linking agent (availableunder the product name “CORONATE L” from Tosoh Corporation) with respectto 100 parts by weight of the solid content of the acrylic polymersolution produced in the foregoing was prepared. The pressure-sensitiveadhesive composition was applied to a separator to form apressure-sensitive adhesive layer having a thickness of 20 μm, and thelayer was bonded to the acrylic resin film to provide an opticallyfunctional film.

The optically functional film (resin layer/pressure-sensitive adhesivelayer containing a coloring matter) obtained as described above wassubjected to the above-mentioned evaluation. The result is shown inTable 1.

TABLE 1 Coloring Transmittance matter-containing layer Coloring matterchange Example 1 Optically functional Squaraine 25.4 layer (moisturecompound permeability: 64 g/m²) Example 2 Optically functional Squaraine9.6 layer (moisture compound permeability: 7 g/m²) ComparativePressure-sensitive Squaraine 44.1 Example 1 adhesive layer (moisturecompound permeability: 7,144 g/m²)

INDUSTRIAL APPLICABILITY

The optically functional film of the present invention is suitably usedin an image display apparatus, such as a liquid crystal displayapparatus.

REFERENCE SIGNS LIST

-   10 optically functional layer-   20 pressure-sensitive adhesive layer-   30 substrate-   100, 100′, 100″ optically functional film

1. An optically functional film, comprising an optically functionallayer having a moisture permeability of 100 g/m² or less, wherein theoptically functional layer has an absorption peak in a wavelength bandin a range of from 580 nm to 610 nm, and wherein the opticallyfunctional layer contains a compound X represented by the followinggeneral formula (I) or general formula (II):

in the formula (I), R₁, R₂, R₃, R₄, R₅, R₆, R₇, and R₈ eachindependently represent a hydrogen atom, a halogen atom, a substitutedor unsubstituted alkyl group having 1 or more and 20 or less carbonatoms, a substituent represented by the formula (a), or a substituentrepresented by the formula (b), R₁ and R₂ form a saturated cyclicskeleton including 5 or 6 carbon atoms, and R₃, R₄, R₅, R₆, R₇, and R₈each independently represent a hydrogen atom, a halogen atom, which ispreferably Cl, a substituted or unsubstituted alkyl group having 1 ormore and 20 or less carbon atoms, a substituent represented by theformula (a), or a substituent represented by the formula (b), R₂ and R₃form a saturated cyclic skeleton including 5 to 7 carbon atoms, and R₁,R₄, R₅, R₆, R₇, and R₈ each independently represent a hydrogen atom, ahalogen atom, which is preferably Cl, a substituted or unsubstitutedalkyl group having 1 or more and 20 or less carbon atoms, a substituentrepresented by the formula (a), or a substituent represented by theformula (b), R₅ and R₆ form a saturated cyclic skeleton including 5 or 6carbon atoms, and R₁, R₂, R₃, R₄, R₇, and R₈ each independentlyrepresent a hydrogen atom, a halogen atom, which is preferably Cl, asubstituted or unsubstituted alkyl group having 1 or more and 20 or lesscarbon atoms, a substituent represented by the formula (a), or asubstituent represented by the formula (b), R₆ and R₇ form a saturatedcyclic skeleton including 5 to 7 carbon atoms, and R₁, R₂, R₃, R₄, R₅,and R₈ each independently represent a hydrogen atom, a halogen atom,which is preferably Cl, a substituted or unsubstituted alkyl grouphaving 1 or more and 20 or less carbon atoms, a substituent representedby the formula (a), or a substituent represented by the formula (b), R₁and R₂ form a saturated cyclic skeleton including 5 or 6 carbon atoms,R₅ and R₆ form a saturated cyclic skeleton including 5 or 6 carbonatoms, and R₃, R₄, R₇, and R₈ each independently represent a hydrogenatom, a halogen atom, which is preferably Cl, a substituted orunsubstituted alkyl group having 1 or more and 20 or less carbon atoms,a substituent represented by the formula (a), or a substituentrepresented by the formula (b), or R₂ and R₃ form a saturated cyclicskeleton including 5 to 7 carbon atoms, R₆ and R₇ form a saturatedcyclic skeleton including 5 to 7 carbon atoms, and R₁, R₄, R₅, and R₈each independently represent a hydrogen atom, a halogen atom, which ispreferably Cl, a substituted or unsubstituted alkyl group having 1 ormore and 20 or less carbon atoms, a substituent represented by theformula (a), or a substituent represented by the formula (b); and in theformula (II), R₄ and R₈ each independently represent a hydrogen atom, ora substituted or unsubstituted alkyl group having 1 or more and 20 orless carbon atoms.
 2. The optically functional film according to claim1, further comprising a pressure-sensitive adhesive layer arranged on atleast one side of the optically functional layer.
 3. The opticallyfunctional film according to claim 1, further comprising a substratearranged on at least one side of the optically functional layer.
 4. Animage display apparatus, comprising the optically functional film ofclaim 1.